Metal etching with in situ plasma ashing

ABSTRACT

In an embodiment, a method includes: receiving, within a processing chamber, a wafer with a photoresist mask above a metal layer, wherein the processing chamber is connected to a gas source; applying an etchant configured to etch the metal layer in accordance with the photoresist mask within the processing chamber; and applying gas from the gas source to perform plasma ashing in the processing chamber.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional PatentApplication No. 62/773,654, filed on Nov. 30, 2018, which isincorporated by reference herein in its entirety.

BACKGROUND

Typical processing of wafers (e.g., semiconductor workpieces,semiconductor devices, or semiconductor materials) may utilize separatechambers for etching and plasma ashing. Etching may be used to removematerial from the surface of a wafer during manufacturing. For example,in etching, parts of the wafer may be protected from etching by amasking material which resists etching. Then, the wafer may be etched byapplication of an etchant to exposed portions of the wafer. Etching istypically performed in an etching chamber specific for etching.

Plasma ashing may be the process of removing the photoresist from anetched wafer. Using a plasma source, a reactive species is generated.The reactive species combines with the photoresist to form ash which maybe removed with a vacuum pump. Plasma ashing is typically performed inan ashing chamber (e.g., a photoresist stripping chamber and/or acooling chamber) that is separate from the etching chamber. Suchprocessing techniques require large amounts of overhead, but still failto produce satisfactory results. Therefore, conventional processingtechniques are not entirely satisfactory.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that various features are not necessarily drawn to scale. In fact,the dimensions and geometries of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a flowchart of a method of metal etching with plasmaashing performed in situ within a semiconductor processing chamberaccording to one or more embodiments of the present disclosure.

FIGS. 2A, 2B, and 2C illustrate cross-sectional views of an exemplarysemiconductor device during various fabrication stages, made by themethod of FIG. 1, in accordance with some embodiments.

FIG. 3 is a diagram of a processing chamber, in accordance with someembodiments.

FIG. 4 is an illustration of a workstation, in accordance with someembodiments.

FIG. 5 is a block diagram of various functional modules of theworkstation, in accordance with some embodiments.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following disclosure describes various exemplary embodiments forimplementing different features of the subject matter. Specific examplesof components and arrangements are described below to simplify thepresent disclosure. These are, of course, merely examples and are notintended to be limiting. For example, it will be understood that when anelement is referred to as being “connected to” or “coupled to” anotherelement, it may be directly connected to or coupled to the otherelement, or one or more intervening elements may be present.

In addition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

The present disclosure provides various embodiments of metal etchingwith plasma ashing performed in situ within a semiconductor processingchamber. In certain embodiments, etching may be performed with aphotoresist mask above a metal layer within the processing chamber(e.g., the semiconductor processing chamber). This processing chambermay be connected to a gas source. In the performance of etching, anexposure system (e.g., a delivery system of an etchant) may be appliedin the processing chamber to etch the metal layer in accordance with thephotoresist mask. Upon the completion of etching, an ashing gas may beapplied from a gas source to perform plasma ashing within the processingchamber. As noted above, this processing chamber may be the same forboth etching and ashing and thus no separate etching chamber,photoresist stripping chamber and/or cooling chamber may be needed.Rather, the functions of each of these may be performed in a singlechamber in a simplified process of etching and plasma ashing. Statedanother way, there may be no de-chucking (e.g., removing an etched waferfrom a chuck it is secured on) between etching and plasma ashing.

In various embodiments, the ashing gas may be at least one of: pureoxygen (O₂), pure nitrogen (N₂), and a mixture of N₂ and O₂. Inparticular embodiments, the mixture of N₂ and O₂ may include less than10 percent of O₂. As will be noted below, the ashing gas may betransformed into plasma within the processing chamber (e.g., via asource power). The O₂ within the plasma may react (e.g., combine) withthe photoresist to produce ash (e.g., removing the photoresist). Morespecifically, the O₂ within the plasma may react (e.g., combine) withthe photoresist to produce carbon dioxide (CO₂), carbon monoxide (CO),and water (H₂O) that may be removed from the processing chamber bysuction forces or a pump. Also, the N₂ within the plasma may react withany residual aluminum chloride (AlCl₃) in the processing chamber. ThisAlCl₃ may be produced as a byproduct of etching. For example, the N₂within the plasma may react with the residual AlCl₃ to produce aluminumnitride (AlN) and chlorine (Cl₂) that may be removed from the processingchamber by suction forces or a pump. The removal of AlCl₃ within theprocessing chamber may decrease the chance of corrosion within theprocessing chamber.

In various embodiments, the plasma ashing may be performed by applying asource power of over 1600 watts. As will be illustrated below, thissource power may be applied to at least one coil within a processingchamber. This processing chamber may have a wall (e.g., a ceiling or adome) that separates the at least one coil from the metal layer. Also,the metal layer may be within a space formed or enclosed by the wall. Inparticular embodiments, the plasma ashing may be performed by applying abias power of about 0 watts. This bias power may be applied at anelectrostatic chuck that supports (e.g., sits on) the wafer that hadpreviously been etched (e.g., previously before plasma ashing). Incertain embodiments, a pressure of less than 100 millitorr may beapplied at the processing chamber during the performance of plasmaashing. Also, the processing chamber may be maintained at about 50degrees centigrade, or at a same temperature at which etching wasperformed. In further embodiments, the processing chamber may bemaintained at a temperature of less than 100 degrees centigrade acrossboth etching and plasma ashing.

In various embodiments, the processing chamber may be part of asemiconductor processing workstation with at least one loadlock foringress or egress of a wafer. In certain embodiments, this wafer mayhave a diameter of about 200 millimeters or a diameter of about 8inches. This semiconductor processing workstation may be configured tomove the wafer from a loadlock to an alignment chamber, from thealignment chamber to the processing chamber, and then from theprocessing chamber to the loadlock for egress of the wafer from thesemiconductor processing workstation (e.g., without moving the waferfrom the processing chamber to a photoresist stripping chamber and/or acooling chamber). Accordingly, the processing chamber may includevarious conduits for ingress of an etchant and an ashing gas as well asfor egress of ash produced during the plasma ashing from the processingchamber via suction forces. In particular embodiments, the processingchamber may be a modified decoupled plasma source (DPS) chamber.

Advantageously, performing in situ plasma ashing may simplifysemiconductor workpiece processing (e.g., semiconductor wafer or deviceprocessing) by not requiring further processing in a photoresiststripping chamber and/or a cooling chamber. Rather, in a singleworkstation with multiple processing chambers, a semiconductor workpiecemay be received in a loadlock, aligned, and then etched and photoresiststripped in a single processing chamber, and then removed from theworkstation without processing at separate etching, photoresiststripping and/or cooling chambers. As noted above, this in situ plasmaashing may include processing under a high source power environment ofover 1600 watts with 0 watts of bias power and in a gaseous environmentwith either a O₂ gas, a N₂, or a gas mixture of N₂ and O₂ gases.Accordingly, etching and plasma ashing may be performed together in asingle processing chamber that is configured with an exposure system(e.g., system for introduction of an etchant) for etching based on aphotoresist mask and an ashing gas source. In particular embodiments, insitu plasma ashing may be performed with the addition of, or alternativeuse of, other gases such as H₂, H₂O, H₂O₂, O₃, CO, CO₂, SO₂, Ar, He, andthe like. In further embodiments, the total wafer temperature during andafter in situ ashing may be less than 100 degrees Celsius, which may berelatively low in comparison to a possible 250 degrees Celsius or morein certain plasma ashing chambers separate from an etching chamber.

FIG. 1 illustrates a flowchart of a method 100 of metal etching withplasma ashing performed in situ within a semiconductor processingchamber according to one or more embodiments of the present disclosure.It is noted that the method 100 is merely an example, and is notintended to limit the present disclosure. Accordingly, it is understoodthat additional operations may be provided before, during, and after themethod 100 of FIG. 1, certain operations may be omitted, and some otheroperations may only be briefly described herein.

In some embodiments, operations of the method 100 may be associated withthe cross-sectional views of a semiconductor device at variousfabrication stages as shown in FIGS. 2A, 2B, and 2C respectively, whichwill be discussed in further detail below.

Referring now to FIG. 1, the method 100 starts with operation 102 inwhich a metal layer with a patterned photoresist is provided at aprocessing chamber. The method 100 continues to operation 104 whereetching is performed within the processing chamber. The method 100continues to operation 106 where plasma ashing is performed in-situ withthe processing chamber that performed the etching.

As mentioned above, FIG. 2A through FIG. 2C illustrate, in across-sectional views, respective portions of a semiconductor device 200at various fabrication stages of the method 100 of FIG. 1. Thesemiconductor device 200 may include, be included in, or be amicroprocessor, memory cell, wafer, and/or other integrated circuit(IC). Also, FIGS. 2A through 2C are simplified for a betterunderstanding of the concepts of the present disclosure. For example,although the figures illustrate the semiconductor device 200, it isunderstood the IC may comprise a number of other devices such asresistors, capacitors, inductors, fuses, etc., which are not shown inFIGS. 2A-2C, for purposes of clarity of illustration.

FIG. 2A is a cross-sectional view of a semiconductor device 200including a photoresist 202 at one of the various stages of fabricationcorresponding to operation 102 of FIG. 1, in accordance with someembodiments. The photoresist 202 may overlay a metal layer 204. Thephotoresist 202 may be patterned such that the photoresist 202 does notcompletely overlay the metal layer 204 but includes various openings 206in which the metal layer 204 is exposed. In various embodiments, themetal layer 204 may be a metal composite layer. This metal compositelayer may include a top layer of, for example, a barrier material thatwill be discussed further below. Optionally, the metal layer may overlayan under layer 208 (e.g., a substrate). As noted above, thesemiconductor device 200 may be part of a wafer resting on (e.g.,secured on and/or contacting) an electrostatic chuck within a processingchamber 210 (illustrated with dotted lines). The processing chamber 210may be a generally enclosed region where both etching and plasma ashingmay take place in-situ. In certain embodiments, the photoresist may beapplied to the metal layer 204 within the processing chamber 210 (e.g.,the photoresist 202 may be put on the metal layer 204 within theprocessing chamber 210). In particular embodiments, the semiconductordevice 200 with the photoresist on top of the metal layer 204 may bereceived at the processing chamber 210.

In some embodiments, the under layer 208 includes a silicon substrate ora silicon oxide substrate. Alternatively, the under layer 208 mayinclude other elementary semiconductor materials such as, for example,germanium. The under layer 208 may also include a compound semiconductorsuch as silicon carbide, gallium arsenic, indium arsenide, and indiumphosphide. The under layer 208 may include an alloy semiconductor suchas silicon germanium, silicon germanium carbide, gallium arsenicphosphide, and gallium indium phosphide. In one embodiment, the underlayer 208 includes an epitaxial layer. For example, the under layer mayhave an epitaxial layer overlying a bulk semiconductor. Furthermore, theunder layer 208 may include a semiconductor-on-insulator (SOI)structure. For example, the under layer may include a buried oxide (BOX)layer formed by a process such as separation by implanted oxygen (SIMOX)or other suitable technique, such as wafer bonding and grinding.

In some embodiments, the under layer 208 also includes variousconductive features, such as p-type doped regions and/or n-type dopedregions, implemented by a process such as ion implantation and/ordiffusion. Those doped regions include n-well, p-well, light dopedregion (LDD), heavily doped source and drain (S/D), and various channeldoping profiles configured to form various active devices (or integratedcircuit (IC) devices), such as a complimentary metal-oxide-semiconductorfield-effect transistor (CMOSFET), imaging sensor, and/or light emittingdiode (LED). The under layer 208 may further include other conductivefeatures, or active devices (functional features) such as a resistor ora capacitor formed in and on the substrate. The under layer 208 mayfurther includes lateral isolation features provided to separate variousconductive features or devices formed in the under layer 208. In oneembodiment, shallow trench isolation (STI) features are used for lateralisolation. The various devices further include silicide disposed on S/D,gate and other device features for reduced contact resistance whencoupled to output and input signals.

In certain embodiments, the under layer 208 may be a dielectric layer.The dielectric layer may form a non-conductive (e.g., dielectric)separation, or isolation, between conductive elements within thesemiconductor device. The dielectric layer may include a non-conductivematerial that is at least one of: silicon oxide, a low dielectricconstant (low-k) material, other suitable dielectric material, or acombination thereof. The low-k material may include fluorinated silicaglass (FSG), phosphosilicate glass (PSG), borophosphosilicate glass(BPSG), carbon doped silicon oxide (SiO_(x)C_(y)), Black Diamond®(Applied Materials of Santa Clara, Calif.), Xerogel, Aerogel, amorphousfluorinated carbon, Parylene, BCB (bis-benzocyclobutenes), SiLK (DowChemical, Midland, Mich.), polyimide, and/or other future developedlow-k dielectric materials.

In certain embodiments, the metal layer 204 may be part of a metal line.For example, the metal layer may be a metal line connected to, or partof, a source, drain or gate electrode of a transistor device, anelectrode of a capacitor, one end of a resistor or of any other activeor passive device. As a further example, the metal layer 204 may connectto other conductive lines and/or vias within the semiconductor device200. In some embodiments, the metal layer 204 may include conductivematerials, such as a metal, or for example, aluminum (Al), copper (Cu),tungsten (W), or a combination thereof. In some other embodiments, themetal layer 204 may include other suitable conductive materials (e.g.,metal materials such as gold (Au), cobalt (Co), silver (Ag), Nickle(Ni), etc. and/or conductive materials (e.g., polysilicon)) whileremaining within the scope of the present disclosure. The metal layer204 may be formed by using chemical vapor deposition (CVD), physicalvapor deposition (PVD), spin-on coating, and/or other suitabletechniques to deposit the metal layer 204 over the under layer 208.

In some embodiments, optionally, the metal layer 204 may include abarrier material on top that enhance (e.g., improves) conductivity ofconductive materials and may effectively prevent (e.g., block) metalatoms from diffusing from conductive materials into non-conductivematerials during a deposition process to form a conductive line.Examples of barrier materials include tantalum nitride (TaN), tantalum(Ta), titanium nitride (TiN), titanium (Ti), cobalt tungsten (CoW),tungsten nitride (WN), or the like.

In the following discussion, reference to the metal layer 204 may or maynot include their corresponding barrier material deposited as a layer ontop of the metal layer 204. In various embodiments, the barrier layerdoes not change the function of any adjoining conductive structureexcept to enhance the material properties of the adjoining conductivestructures.

In particular embodiments, the photoresist 202 may be a light-sensitivematerial used to etch the metal layer 204. This photoresist 202 may beapplied on top of the metal layer 204. In certain embodiments, thisphotoresist 202 may be applied directly on top of the metal layer 204(e.g., directly contacting the uniform material of the metal layer 204).In further embodiments, the photoresist 202 may be applied on top of themetal layer 204 such that the photoresist 202 is on top of a barriermaterial of the metal layer 204 (e.g., a layer of barrier material thatforms the upper surface of the metal layer 204.)

In certain embodiments, the photoresist 202 may be a light-sensitiveorganic material deposited on the metal layer 204. The photoresist maybe formed (e.g., patterned) by applying a patterned mask to block lightincident upon the photoresist, so that only unmasked regions of thematerial will be exposed to light. A solvent, may then applied to thephotoresist. In the case of a positive photoresist, the photoresistmaterial is degraded by light and the solvent will dissolve away theregions that were exposed to light, leaving behind the photoresist wherethe patterned mask was placed. In the case of a negative photoresist,the photosensitive material is strengthened (e.g., polymerized orcross-linked) by light, and the solvent will dissolve away only theregions that were not exposed to light, leaving behind the photoresistin areas where the patterned mask was not placed. As will be discussedfurther below, the photoresist may then be used as a mask to perform oneor more dry/wet etching processes to respectively or simultaneously etchthe metal layer 204.

FIG. 2B is a cross-sectional view of the semiconductor device 200 afteretching at one of the various stages of fabrication that corresponds tooperation 106 of FIG. 1, in accordance with some embodiments. Morespecifically, the semiconductor device 200 after etching may form anetched metal layer 222. This etched metal layer 222 may be formed byusing the photoresist 202 as a mask to perform one or more etchingprocesses to respectively or simultaneously etch the metal layer to formthe etched metal layer 222. A wet etching process may reference use of awet etchant for etching and a dry etching process may reference use of adry etchant for etching. Examples of a wet etchant may include, forexample, hydrofluoric acid (HF), phosphoric acid (H₃PO₄), acetic acid,nitric acid (HNO₃), water (H₂O), and the like. Examples of a dry etchant(also referred to as an etchant plasma or an etchant gas) may include,for example, tetrafluoromethane (CF₄), fluoroform (CHF₃),difluoromethane (CH₂F₂), octafluorocyclobutane (C₄F₈), argon (Ar),oxygen (O₂), and the like.

In various embodiments, when the metal layer is aluminum (Al), anapplied wet etchant for wet etching may be, for example, 80% phosphoricacid (H₃PO₄)+5% acetic acid+5% nitric acid (HNO₃)+10% water (H₂O)applied at about 50 degrees centigrade, or from about 30 degreescentigrade to about 60 degrees centigrade. In further embodiments, whenthe metal layer is aluminum (Al), an applied dry etchant may be, forexample, Cl₂, CCl₄, SiCl₄, and/or BCl₃ at about 50 degrees centigrade,or from about 30 degrees centigrade to about 60 degrees centigrade. Inparticular embodiments, etching may produce an etching byproduct, AlCl₃.

In particular embodiments, a polymer 224 may be present on the sidewallsof the etched metal layer 222. This polymer may be a byproduct ofetching the metal layer to form the etched metal layer 222. In additionto the formation of the etched metal layer 222, etching of thesemiconductor device 200 may also cause some etching (e.g., erosion) ofthe photoresist 202 and the under layer 208 as illustrated in FIG. 2B.In particular embodiments, etching may produce an etching byproduct,AlCl₃.

FIG. 2C is a cross-sectional view of the semiconductor device 200 afterplasma ashing at one of the various stages of fabrication thatcorresponds to operation 106 of FIG. 1, in accordance with someembodiments. Plasma ashing may refer to a process of removing thephotoresist after etching. As illustrated, after plasma ashing, theetched metal layer 222 may not include an overlaying photoresist. Morespecifically, using a plasma source, a monatomic (single atom) substance(also referred to as a reactive species or an ashing gas) may beintroduced to the processing chamber 210. The ashing gas may combinewith the photoresist to form ash which is removed from the processingchamber 210 with a vacuum pump.

In various embodiments, plasma is created by exposing the ashing gas(e.g., reactive species) at a low pressure to high power radio waves,which ionise the ashing gas. This process may be done under vacuum inorder to better create the plasma. In certain embodiments, the plasmamay be generated in situ in the process chamber. However, in otherembodiments, the plasma may be formed remotely from the process chamberwhere the desired particles for ashing are separated from the formedplasma and channeled to the wafer within the process chamber. By formingthe plasma remotely, electrically charged particles may have time torecombine before they reach the photoresist surface to avoid damage tothe wafer surface from plasma formation.

In various embodiments, the ashing gas may be at least one of: pureoxygen (O₂), pure nitrogen (N₂), and a mixture of N₂ and O₂. Inparticular embodiments, the mixture of N₂ and O₂ may include less than10 percent of O₂. The ashing gas may be transformed into plasma withinthe processing chamber (e.g., via a source power for high power radiowaves). For example, O₂ may be used as a major plasma source to reactwith the photoresist in accordance with the below formula:

CxHyOz+O₂

CO₂+CO+H₂O   (1)

The CxHyOz may represent the photoresist, the O₂ may represent theplasma, and the CO₂+CO+H₂O may be removed by a pump (e.g., via suctionforces from the processing chamber). Stated another way, the O₂ withinthe plasma may react (e.g., combine) with the photoresist to produce ash(e.g., removing the photoresist). More specifically, the O₂ within theplasma may react (e.g., combine) with the photoresist to produce carbondioxide (CO₂), carbon monoxide (CO), and water (H₂O) that may be removedfrom the processing chamber by suction forces or a pump.

Also, N₂ may be used to react with an etch byproduct AlCl₃ (introducedabove) to avoid corrosion in accordance with the below formula:

AlCl₃+N₂

AlN+Cl₂   (2)

The AlCl₃ may represent a byproduct, the N₂ may represent the plasma,and the resultant AlN+Cl₂ may be removed by a pump (e.g., via suctionforces from the processing chamber). Stated another way, the N₂ withinthe plasma may react with the residual AlCl₃ to produce aluminum nitride(AlN) and chlorine (Cl₂) that may be removed from the processing chamberby suction forces or a pump. The removal of AlCl₃ within the processingchamber may decrease the chance of corrosion within the processingchamber.

Accordingly, in various embodiments, the corrosion formula may berepresented in a chain reaction as follows:

AlCl₃+3H₂P

Al(OH)₃+3HCl   (3)

Al(OH)₃+3HCl+3H₂O

Al₂O₃+9H₂O+6HCl   (4)

2Al+6HCl

2AlCl₃+3H₂   (5)

In various embodiments, the plasma ashing may be performed by applying asource power of over 1600 watts. As will be illustrated below, thissource power may be applied to at least one coil within a processingchamber with a wall (e.g., a ceiling or a dome) that has multiple coilsseparated from an etched metal layer facing by the wall. In particularembodiments, the plasma ashing may be performed by applying a bias powerof about 0 watts. This bias power may be applied at an electrostaticchuck that supports the wafer that had previously been etched (e.g.,previously before plasma ashing). In certain embodiments, a pressure ofless than 100 millitorr may be applied the processing chamber during theperformance of plasma ashing. Also, the processing chamber may bemaintained at range of 40 to 60 degrees centigrade. In some embodiments,the processing chamber temperature is about 50 degrees centigrade.Although certain processing conditions may be utilized in certainembodiments, other processing conditions may be utilized in otherembodiments as desired for different applications in variousembodiments.

FIG. 3 is a diagram of a processing chamber 300, in accordance with someembodiments. The processing chamber 300 may include an enclosed area 302in which both metal etching and plasma ashing are performed in situ. Theprocessing chamber may include a wall 303 that defines the enclosed area302. In certain embodiments, the wall 303 may be formed substantially asa dome. A wafer 304 may be located within the enclosed area 302 foretching and plasma ashing. More specifically, this wafer 304 may includea metal layer for etching within the enclosed area 302 of the processingchamber 300. An etchant may be provided into the processing chamber 300via an etchant conduit 306 from an etchant source (not illustrated).This etchant conduit 306 may, for example, provide an etchant that is anwet etchant for wet etching and/or a dry etchant for dry etching.Examples of a wet etchant may include, for example, hydrofluoric acid(HF), phosphoric acid (H₃PO₄), acetic acid, nitric acid (HNO₃), water(H₂O), and the like. Examples of a dry etchant (also referred to as anetchant plasma or an etchant gas) may include, for example,tetrafluoromethane (CF₄), fluoroform (CHF₃), difluoromethane (CH₂F₂),octafluorocyclobutane (C₄F₈), argon (Ar), oxygen (O₂), and the like.

In various embodiments, when the metal layer is aluminum (Al), anapplied wet etchant for wet etching may be, for example, 80% phosphoricacid (H₃PO₄)+5% acetic acid+5% nitric acid (HNO₃)+10% water (H₂O)applied at about 50 degrees centigrade, or from about 30 degreescentigrade to about 60 degrees centigrade. In further embodiments, whenthe metal layer is aluminum (Al), an applied dry etchant may be, forexample, Cl₂, CCl₄, SiCl₄, and/or BCl₃ at about 50 degrees centigrade,or from about 30 degrees centigrade to about 60 degrees centigrade. Inparticular embodiments, etching may produce an etching byproduct, AlCl₃.

As noted above, plasma ashing may be performed in situ within theenclosed area 302 of the processing chamber 300 (e.g., in the samelocation in which etching was performed). Plasma ashing may refer to aprocess of removing the photoresist after etching. An ashing gas may beprovided into the processing chamber 300 via an ashing conduit 310 froman ashing gas source (not illustrated) for plasma ashing. This ashingconduit 310 may, for example, provide an ashing gas for plasma ashingwithin the enclosed area 302 of the processing chamber 300. This ashinggas may be, for example, a monatomic (single atom) substance (alsoreferred to as a reactive species). The ashing gas may combine with thephotoresist to form ash which is removed from the processing chamber 210with a vacuum pump 312 (e.g., removed via suction forces).

In various embodiments, plasma 314 is created by exposing the ashing gas(e.g., reactive species) at a low pressure (e.g., less than 100millitorr) to high power radio waves, which ionise the ashing gas. Incertain embodiments, this process may be done under vacuum in order tobetter create the plasma 314. In various embodiments, the ashing gas maybe at least one of: pure oxygen (O₂), pure nitrogen (N₂), and a mixtureof N₂ and O₂. In particular embodiments, the mixture of N₂ and O₂ mayinclude 0 to 10 percent of O₂.

In particular embodiments, the plasma ashing may be performed byapplying a source power 316 of over 1600 watts. This source power 316may be applied each of a number of coils 318 within the processingchamber. For simplicity of illustration, the connection between thesource power 316 and the coils 318 is only illustrated with a singleconnection with a single coil to represent the respective connectionsfrom each of the coils 318 to the source power 316.

In further embodiments, the enclosed area 302 may include anelectrostatic chuck 320 on which the wafer 304 is secured. Theelectrostatic chuck 320 may be supplied with a bias power 322 (e.g., aradio frequency bias power). This bias power may be applied to calibratethe amount of downward force the plasma 314 may experience to bombardthe wafer 304. In certain embodiments, the bias power may be about 0watts during plasma ashing. In certain embodiments, a pressure of lessthan 100 millitorr may be applied the processing chamber during theperformance of plasma ashing. Also, the processing chamber may bemaintained at about 50 degrees centigrade. In particular embodiments,after plasma ashing the wafer 304 may be de-chucked (e.g., removed fromthe electrostatic chuck 320 and removed from the processing chamber 300(e.g., via a robotic arm).

FIG. 4 is an illustration of a workstation 400, in accordance with someembodiments. The workstation 400 may include loadlocks 404A, 404B, atransfer chamber 406, an alignment chamber 408, and multiple processingchambers 410A-410D for both etching and plasma ashing in situ withineach of the multiple processing chambers 410A-410D.

The transfer chamber 406 may include a first robotic arm 412A and asecond robotic arm 412B. The first robotic arm 412A and the secondrobotic arm 412B may be referred to as a robotic arm system. The roboticarm system of the first robotic arm 412A and the second robotic arm 412Bmay be configured to transfer wafers among the loadlocks 404A, 404B, thealignment chamber 408, and the multiple processing chambers 410A-410D.The first robotic arm 412A may be opposite the second robotic arm 412Band thus the robotic arm system may be configured to handle up to twowafers at a single time. Also, the robotic arm system may be configuredto swivel about to face each of the loadlocks 404A, 404B, the alignmentchamber 408, and the multiple processing chambers 410A-410D as desired.Also, each robotic arm 412A and 412B may be configured to extend and/orretract from the loadlocks 404A, 404B, the alignment chamber 408, and/orthe multiple processing chambers 410A-410D as desired to place and/orremove a wafer from the loadlocks 404A, 404B, the alignment chamber 408,and/or the multiple processing chambers 410A-410D as desired.Furthermore, each of the loadlocks 404A, 404B, the alignment chamber408, and/or the multiple processing chambers 410A-410D may include aportal into and from which each robotic arm 412A and 412B may extend.Accordingly, each respective portal may also close to seal each of theloadlocks 404A, 404B, the alignment chamber 408, and/or the multipleprocessing chambers 410A-410D when access via the robotic arm 412A and412B is not desired.

The loadlocks 404A, 404B may be configured to interface with a systemexternal to the workstation 400. For example, the loadlocks 404A, 404Bmay be configured to interface with an automated material handlingsystem that may place and/or remove wafers from the loadlocks 404A,404B.

The alignment chamber 408 may be configured to align a wafer on therobotic arm system. For example, the alignment chamber 408 may include asensor and/or an actuator to determine an orientation of the wafer onthe robotic arm system (e.g., when on or interfaced with the robotic arm412A 412B) and to move the wafer into a desired orientation (e.g.,angular orientation) with the robotic arm system. Then, the robotic armsystem may move and deposit the wafer with the desired orientation onthe robotic arm system into one of the multiple processing chambers410A-410D.

Each of the multiple processing chambers 410A-410D may include anenclosed area in which both metal etching and plasma ashing areperformed in situ. Accordingly, each processing chamber 410A-410D mayinclude a wall that defines the enclosed area. In certain embodiments,the wall may be formed substantially as a dome. A wafer may be locatedwithin the enclosed area for etching and plasma ashing. Morespecifically, this wafer may include a metal layer for etching withinthe enclosed area of each processing chamber 410A-410D. An etchant maybe provided into each processing chamber 410A-410D via an etchantconduit from an etchant source (not illustrated). This etchant conduitmay, for example, provide an etchant that is an wet etchant for wetetching and/or a dry etchant for dry etching.

In various embodiments, when the metal layer is aluminum (Al), anapplied wet etchant for wet etching may be, for example, 80% phosphoricacid (H₃PO₄)+5% acetic acid+5% nitric acid (HNO₃)+10% water (H₂O)applied at about 50 degrees centigrade, or from about 30 degreescentigrade to about 60 degrees centigrade. In further embodiments, whenthe metal layer is aluminum (Al), an applied dry etchant may be, forexample, Cl₂, CCl₄, SiCl₄, and/or BCl₃ at about 50 degrees centigrade,or from about 30 degrees centigrade to about 60 degrees centigrade. Inparticular embodiments, etching may produce an etching byproduct, AlCl₃.

As noted above, plasma ashing may be performed in situ within theenclosed area of each processing chamber 410A-410D (e.g., in the samelocation in which etching was performed). An ashing gas may be providedinto each processing chamber 410A-410D via an ashing conduit from anashing gas source (not illustrated) for plasma ashing. This ashingconduit may, for example, provide an ashing gas for plasma ashing withinthe enclosed area of each processing chamber 410A-410D. The ashing gasmay combine with the photoresist to form ash which is removed from eachprocessing chamber 410A-410D with a respective vacuum pump.

In various embodiments, plasma 314 is created by exposing the ashing gas(e.g., reactive species) at a low pressure (e.g., less than 100millitorr) to high power radio waves, which ionise the ashing gas. Thisprocess may be done under vacuum in order to better create the plasma314. In various embodiments, the ashing gas may be at least one of: pureoxygen (O₂), pure nitrogen (N₂), and a mixture of N₂ and O₂. Inparticular embodiments, the mixture of N₂ and O₂ may include less than10 percent of O₂.

In particular embodiments, the plasma ashing may be performed byapplying a source power of over 1600 watts. This source power may beapplied at each of a number of coils within each processing chamber410A-410D. Also, each processing chamber 410A-410D may include anelectrostatic chuck configured to secure a wafer during plasma ashing.The electrostatic chuck may be supplied with a bias power (e.g., a radiofrequency bias power). In certain embodiments, the bias power may beabout 0 watts during plasma ashing. In certain embodiments, a pressureof less than 100 millitorr may be applied in each processing chamber410A-410D during the performance of plasma ashing. Also, each processingchamber 410A-410D may be maintained at about 50 degrees centigrade. Inparticular embodiments, after plasma ashing the wafer may be de-chucked(e.g., removed from the electrostatic chuck) and removed from arespective processing chamber 410A-410D via the first robotic arm 412Aand/or the second robotic arm 412B. The wafer may then be moved back toone of the loadlocks 404A, 404B for egress from the workstation 400.

Accordingly, a wafer may be received at one of the loadlocks 404A, 404B.Then, the wafer may be aligned at the alignment chamber 408 (e.g.,aligned with reference to the robotic arm system of the first roboticarm 412A and the second robotic arm 412B). Then, the wafer may beprocessed at one of the processing chambers 410A-410D in which bothmetal etching and plasma ashing are performed in situ (e.g., withoutde-chucking between the metal etching and plasma ashing). Then, finally,the wafer may be moved to one of the loadlocks 404A, 404B for egressfrom the workstation 400. Movement among the loadlocks 404A, 404B, thealignment chamber 408, and/or the multiple processing chambers 410A-410Dmay be made via the robotic arm system of the first robotic arm 412A andthe second robotic arm 412B. Various arrows are illustrated over theworkstation 400 to illustrate the path of a wafer for processing at theworkstation 400. Accordingly, the wafer may be processed at one of butnot more than one of the processing chamber 410A-410D.

FIG. 5 is a block diagram of various functional modules of theworkstation 400, in accordance with some embodiments. As noted above,the workstation 400 may include loadlocks, a transfer chamber, analignment chamber, and multiple processing chambers for both etching andplasma ashing in situ within each of the multiple processing chambers.The workstation 400 may also include a processor 504. In furtherembodiments, the processor 504 may be implemented as one or moreprocessors.

The processor 504 may be operatively connected to a computer readablestorage module 506 (e.g., a memory and/or data store), a networkconnection module 508, a user interface module 510, a controller module512, and a sensor module 514. In some embodiments, the computer readablestorage module 506 may include workstation logic that may configure theprocessor 504 to perform the various processes discussed herein. Thecomputer readable storage 506 may also store data, such as sensor datacharacterizing wafer alignment with the robotic arm system, controlinstructions for a robotic arm to align a wafer, identifiers for awafer, identifiers for a workstation, identifiers for a semiconductorworkpiece fabrication process, and any other parameter or informationthat may be utilized to perform the various processes discussed herein.

The network connection module 508 may facilitate a network connection ofthe workstation 400 with various devices and/or components of theworkstation 400 that may communicate (e.g., send signals, messages,instructions, or data) within or external to the workstation 400. Incertain embodiments, the network connection module 508 may facilitate aphysical connection, such as a line or a bus. In other embodiments, thenetwork connection module 508 may facilitate a wireless connection, suchas over a wireless local area network (WLAN) by using a transmitter,receiver, and/or transceiver. For example, the network connection module508 may facilitate a wireless or wired connection with the processor 504and the computer readable storage 506.

The workstation 400 may also include the user interface module 510. Theuser interface may include any type of interface for input and/or outputto an operator of the workstation 400, including, but not limited to, amonitor, a laptop computer, a tablet, or a mobile device, etc.

The workstation 400 may include a controller module 512. The controllermodule 512 may be configured to control various physical apparatusesthat control movement or functionality for a robotic arm, portal,processing chamber, valve, or any other controllable aspect of theworkstation 400. For example, the controller module 512 may beconfigured to control movement or functionality for at least one of aportal of one of the loadlocks, the alignment chamber, and/or theprocessing chamber, a rotational motor that rotates the robotic armsystem around an axis of rotation, and the like. For example, thecontroller module 512 may control a motor or actuator. The controllermay be controlled by the processor and may carry out the various aspectsof the various processes discussed herein.

The sensor module 514 may represent a sensor configured to collectsensor data. As discussed above, in certain embodiments this sensor maycollect sensor data characterizing wafer alignment with the robotic armsystem. In other embodiments, this sensor may be configured to collectsensor data that characterizes how metal etching and/or plasma ashing isbeing performed within a processing chamber for both etching and plasmaashing in situ.

In an embodiment, a method includes: receiving, within a processingchamber, a wafer with a photoresist mask above a metal layer, whereinthe processing chamber is connected to a gas source; applying an etchantconfigured to etch the metal layer in accordance with the photoresistmask within the processing chamber; and applying gas from the gas sourceto perform plasma ashing in the processing chamber.

In another embodiment, a method includes: receiving, within a processingchamber, a wafer with a photoresist mask above a metal layer, whereinthe processing chamber is connected to a gas source; applying an etchantconfigured to etch the metal layer in accordance with the photoresistmask within the processing chamber; applying gas from the gas source toperform plasma ashing in the processing chamber; and removing ashproduced during the plasma ashing from the processing chamber.

Yet in another embodiment, a processing chamber includes: anelectrostatic chuck configured to secure a wafer, the electrostaticchuck connected with a bias power; at least one coil connected with asource power; a system configured provide an etchant to a metal of thewafer within the processing chamber in accordance with a photoresistmask of the wafer; and a gas intake conduit connected with a gas source,wherein the gas intake conduit is configured to supply the processingchamber with a gas from the gas source during performance of plasmaashing within the processing chamber.

The foregoing outlines features of several embodiments so that thoseordinary skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodimentsintroduced herein. Those skilled in the art should also realize thatsuch equivalent constructions do not depart from the spirit and scope ofthe present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

Conditional language such as, among others, “can,” “could,” “might” or“may,” unless specifically stated otherwise, are otherwise understoodwithin the context as used in general to convey that certain embodimentsinclude, while other embodiments do not include, certain features,elements and/or steps. Thus, such conditional language is not generallyintended to imply that features, elements and/or steps are in any wayrequired for one or more embodiments or that one or more embodimentsnecessarily include logic for deciding, with or without user input orprompting, whether these features, elements and/or steps are included orare to be performed in any particular embodiment.

Disjunctive language such as the phrase “at least one of X, Y, or Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to present that an item, term, etc., may beeither X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z).Thus, such disjunctive language is not generally intended to, and shouldnot, imply that certain embodiments require at least one of X, at leastone of Y, or at least one of Z to each be present.

It should be emphasized that many variations and modifications may bemade to the above-described embodiments, the elements of which are to beunderstood as being among other acceptable examples. All suchmodifications and variations are intended to be included herein withinthe scope of this disclosure and protected by the following claims.

What is claimed is:
 1. A method, comprising: receiving, within aprocessing chamber, a wafer with a photoresist mask above a metal layer,wherein the processing chamber is connected to a gas source; applying anetchant configured to etch the metal layer in accordance with thephotoresist mask within the processing chamber; and applying gas fromthe gas source to perform plasma ashing in the processing chamber. 2.The method of claim 1, wherein the gas is at least one of: pure O₂, pureN₂, and a mixture of N₂ and O₂.
 3. The method of claim 2, wherein themixture of N₂ and O₂ comprises 0 to 10 percent of O₂.
 4. The method ofclaim 1, further comprising: applying a source power of over 1600 wattsto perform the plasma ashing.
 5. The method of claim 4, wherein theprocessing chamber comprises a wall with a coil facing a first surfaceof the wall and with the metal layer facing a second surface of the wallopposite the first surface, wherein the source power is applied to atleast one coil.
 6. The method of claim 1, further comprising: applying abias power of about 0 watts to perform the plasma ashing.
 7. The methodof claim 6, wherein the wafer contacts an electrostatic chuck, and thebias power is applied to the electrostatic chuck.
 8. A method,comprising: receiving, within a processing chamber, a wafer with aphotoresist mask above a metal layer, wherein the processing chamber isconnected to a gas source; applying an etchant configured to etch themetal layer in accordance with the photoresist mask within theprocessing chamber; applying gas from the gas source to perform plasmaashing in the processing chamber; and removing ash produced during theplasma ashing from the processing chamber.
 9. The method of claim 8,further comprising: applying a pressure of less than 100 millitorrthroughout the processing chamber to perform the plasma ashing.
 10. Themethod of claim 8, further comprising: maintaining the processingchamber at about 50 degrees centigrade to perform the plasma ashing. 11.The method of claim 8, further comprising: transforming the gas from thegas source into a form of plasma to perform the plasma ashing in theprocessing chamber.
 12. The method of claim 8, wherein the metal layeris formed on top of an under layer comprising silicon oxide.
 13. Themethod of claim 8, wherein the gas from the gas source comprises O₂. 14.The method of claim 13, wherein the gas from the gas source comprises 0to 10 percent of O₂.
 15. A processing chamber, comprising: anelectrostatic chuck configured to secure a wafer, the electrostaticchuck connected with a bias power; at least one coil connected with asource power; a system configured provide an etchant to a metal of thewafer within the processing chamber in accordance with a photoresistmask of the wafer; and a gas intake conduit connected with a gas source,wherein the gas intake conduit is configured to supply the processingchamber with a gas from the gas source during performance of plasmaashing within the processing chamber.
 16. The processing chamber ofclaim 15, wherein the processing chamber is part of a semiconductorprocessing workstation with a loadlock for ingress or egress of thewafer.
 17. The processing chamber of claim 16, wherein the semiconductorprocessing workstation is configured to move the wafer from an alignmentchamber to the processing chamber, and then to the loadlock for egressof the wafer from the processing chamber.
 18. The processing chamber ofclaim 15, wherein the processing chamber comprises a suction conduitconfigured to remove ash produced during the plasma ashing from theprocessing chamber via suction forces.
 19. The processing chamber ofclaim 15, wherein the metal comprises aluminum.
 20. The processingchamber of claim 15, wherein the metal comprises aluminum with a toplayer of titanium nitride (TiN).